Slack adjuster



w. w. HUNZICKER.

SLA'CK ADJUSTER.

APPLICATION FILED AUG. 18. 19w.

1,341,321. Patented May 25, 1920.

so as 17 24 2a 2a UNITED STATES PATENT OFFICE.

WALTER W. HUNZICKER, OF MANSFIELD, OHIO, ASSIGNOR TO THE OHIO BRASS COMPANY, OF MANSFIELD, OHIG, A CORPORATION OF NEW JERSEY.

SLACK ADJUSTER.

Specification of Letters Patent.

Patented May 25, 1920.

Application filed August 18, 1919. Serial No. 318,128.

To all whomv it may concern Be it known that I, WALTER W. HUN- ZIcKnn, a citizen of the United States of rhnerica residing at Mansfield, in the county of Richland and State of Ohio, have invented certain new and useful Improvements in SlackAdjusters, of which the following is a specification.

This invention relates to improvements in slack adjusters and has particular reference to the type of slack adjusters adapted to be secured to and connect the lower ends of the live and dead levers of railway brake riggings, or the like, and which operate to take up and hold slack caused by wear thereby to maintain a uniform piston travel at allitimes.

The primary object of the present invention is to provide an improved device of the character referred to which will be practical and which will operate to maintain the brake rigging in a high state of efficiency. Another object is to provide a slack adjuster which will be simple, durable and compact in construction, and which when once installed will not require further attention or adjustment. A further object is to provide an automatic slack adjuster which can be applied to trucks of various types now in use without material modification and which will be inexpensive to manufacture.

To the attainment of these ends and the accomplishment of other new and useful objects, as will. appear, the invention consists in the novel features of construction, combination and relation of the various parts to be hereinafter more fully described and claimed, and shown in the accompany ing drawings and in which Figure 1 is a side elevational view of a conventional brake rigging showing only such parts as are necessary to illustrate the embodiment of one form of the present in vention and in which the brakes are shown as released.

Fig. 2 is an enlarged side elevational view of the slack adjuster shown in Fig. 1, and embodying my invention.

Fig. 3 is a bottom view of the device shown partly in section. substantially on line of Fig. 2 and illustrates the constructional arrangement of the various parts.

While I have shown my invention as applied to a beamless truck it will be understood that it is not limited thereto and that it may be applied to other types of trucks and brake riggings equally as well and without departing from the spirit and scope of this invention.

In the drawings similar reference char acters refer to similar parts throughout the various vlews.

Referring to the drawings which 'illustrate the preferred embodiment of my invention shown in Fig. 1 as applied to a beamless truck comprising the usual truck bolster 1 having positioned at either side thereof wheels 2-, each provided with a brakeshoe 3 pivotally supported by the live and dead levers 4; and 5 respectively.

The dead lever 5 is pivotally supported at its upper end by means of a bracket 6 secured to the bolster 1, while the corresponding end of the live lever 4 is shown as connected to one end of a. pull rod 7 which in turn is connected to the brake actuating mechanism, not illustrated in the drawings.

Pivotally connecting the lower ends of the live and dead levers is an adjustable push rod or slack adjuster adapted to take up and hold slack as occasioned by wear of parts in the brake rigging and which forms the subject matter of the present invention and will now be described.

As shown more clearly in Fig. 3 the push rod comprises two parts in telescopic relation, one of which is a tubular member 8 provided at one end with an enlarged housing or chamber 9 and having its opposite end. pivotally connected at 10 to the lower end of the dead lever 5 by means of a bolt 11. The other part of the push rod is a solid rod 12 slidably mounted within the tubular member 8 and having its free end pivotally connected to the lower end of the live lever 4 as by means of the bolt 13. For the purpose of holding the parts 8 and 12 in extended or adjusted positions I preferably arrange a plurality of holding dogs or grips 14 within the chamber 9. These grips have openings through which the rod 12 passes and are normally held in canted or holding position by means of a spring 15 arranged within the chamber as shown and in which position the grips operate to prevent inward telescopic movement of the parts 8 and 12 but permit free outward movement thereof in a manner well understood in the art. These holding dogs or grips are well known in the art and I wish it understood that my invention is not limited thereto, as various other take-up and holding means such as shims, wedges, screw threads, or the like, may be employed within the scope of this invention.

For the purpose of extending or adjusting the parts 8 and 12 to take up and hold slack, I provide an auxiliary adjusting device adapted to hold one of the parts of the telescopic push rod while the other part is being pulled out or extended. This device comprises an adjusting bar 16 passing through openings formed in the walls of an auxiliary housing or chamber 17 prefer ably formed integrally with the housing 9 and having one end 18 thereof turned upwardly and provlded with an elongated slot 19 adapted to slidably receive the pin 20 which forms the fulcrum point of the live lever 4, as will be described hereinafter. The elongated slot 19 permits predetermined lost motion travel of the live lever for brake shoe clearance as is well understood in the art.

Slidably mounted in suitable apertures provided in the end walls of the chamber 17 are oppositely projecting stems 21 and 22 of a movable stop member 23 arranged within the chamber 17, the purpose of which will be described hereinafter. This stop is yieldably and adjustably maintained in operative position by means of a spring 2el mounted upon the stem 22 and held under compression between the stop 23and inner surface of the end wall 25 of the chamber by means of an adjusting nut 26 threadedly secured to the end of the stem 22 projecting through the chamber 17.

Mounted upon the adjusting rod 16 within the chamber 17 is a grip 27, any number of which may be employed. This grip is normally held in canted or holding position against the stop 23 by means of a spring 28 mounted upon the adjusting bar 16 and compressed between the grip 27 and the end wall 29 of the chamber 17. When operating under normal conditions the grip is maintained in canted position on the bar, as clearly shown in Fig. 2, and in which position it is interlocked with the bar 16 against relative movement in one direction in a manner well understood in the art but permits free movement of the bar in the opposite direction, indicated by arrow A, and in which direction the bar is adapted to move under normal operation to take up slack. Under certain abnormal conditions, however, such as heavy car loading or rapid braking, it is necessary that a slight sliding moven'lent of the bar in the opposite direction indicated by arrow B should take place to avoid bending of the adjusting bar, tight brakes, or other injury to the brake rigging. This I accomplish by providing a tripping lug 30 preferably formed integrally with the housing 17 and which operates to trip or release. the grip 27 when brought into engagement with the lug by movement of the bar 16 and grip 27 in the direction indicated by arrow B, thus permitting free movement of the bar in this direction. This movement of the bar actuates the stop 23 and compresses the spring 24: which yields under pressure. From the foregoing it will be obvious that the adjusting bar is free to move in either direction and that outward movement indicated by arrow A is accompanied by very little resistance while inward movement indicated by arrow B is effectively resisted by action of the spring 21. It will be noted that by varying the tension of the spring 2-1v the parts may be adjusted to require any predetermined amount of pressure upon the bar to effect inward movement thereof.

In order that a clear understanding of the invention may be had a brief statement of the operation is as followsz-When the brakes are released the live and dead lovers are disposed as shown in Fig. 1, and the brake shoes are held out of engagement with the wheels. On application of the brakes the rod 7 moves toward the right which carries the upper end of the live lever 4 therewith and causes the adjacent brake shoe to move toward and into engagement with the periphery of the adjacent wheel and react through the push rod or slack adjuster to move the opposite brake shoe into engagement with the adjacent wheel by moving the lower end of the dead lever 5 toward the left about its fixed pivotal point. During this movement of the live lever the pin 20 moves from one end of the lost motion slot 19 to the other end thereof without imparting movement to the adjusting bar 16, providing there is no lost motion or slack to be taken up. Upon release of the brakes the usual return springs, not shown, will tend to restore the levers to normal position and cause the brake shoes to drop away from the wheels as perm itted by reason of the elongated or lost motion slot 19. This operation will continue indefinitely so long as there is no lost motion to be taken up. Continued application of the brake, however, is accompanied by brake shoe wear which permits excess travel of the live lever beyond the lost motion allowed by the elongated slot 19 for brake shoe clearance. This excessive movement of the live lever when' applying the brakes, imparts outward movement to the adjusting bar 16 an amount equal thereto. On release of the brakes the upper end of the live lever moves toward the left, causing the live and dead levers with their respective brake shoes to drop away from the wheels as allowed by the elongated or lost motion slot 19 and as the adjusting bar has been moved outwardly or extended, the grip 27 will then hold while the pivot pin 20 acts as a fulcrum about which the live lever rotates during a portion of the full return movement of the same, thus causing the lower end of the live lever to movetoward the right and pull out the rod 12 from the tubular member 8 an amount equal to the excess travel of the levers. The rod 12 is free to move through the dogs or grips 14 toward the right or outwardly but is prevented from moving in the opposlte direction or toward the left on application of the brakes by reason of the canted position of the dogs.

The device operates as above described under normal conditions to take up and hold excessive movement of the levers caused by brake shoe and adjacent rigging wear. In actual operation, however, certain types of trucks under abnormalconditions, as hereinbefore stated, permit downward movement of the brakes and rigging as well as toward the wheels which causes excessive movement of the levers and associated rigging irrespective of wear of the parts and upon release of the brakes, when the parts are in this abnormal lowered position, the adjustin bar will be subjected to excessive pressure during the return movement of the live lever. It is at this point that the grip 27 yields to inward movement of the adjusting bar as hereinbefore described, thereby preventing injury to the rigging.

Having thus fully described my invention and illustrated one embodiment of the same, 1 do not wish to be limited to the details of the construction shown since these can obviously be changed without departing from the spirit and scope of the invention.

I claim z- 1. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with anauxiliary adjusting device, said device embodying an adjusting bar slidably connected to said push rod, a grip mounted on the bar, means for yieldingly holding the grip in canted position to prevent inward movement of the bar when subjected to a pressure less than a predetermined value, and means for tripping the grip to permit inward movement of the bar when subjected to the predetermined pressure.

2. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device, said device embodying an adjusting bar slidably supported by said push rod, and a connection between the rod and bar adapted to permit free outward movement of the bar and to yield to inward the rod, a grip on the bar and held 'interlocked therewith against relative movement in one direction by engagement with the stop, and means for releasing the grip when actuated by movement of the bar in one direction, as described.

4. An automatic slack adjuster comprising an adjustable push rod and holding means to maintain the rod in extended position, in combination with an adjusting device adapted to extend the rod to take up slack, said device including an adjustingbar supported by the rod for relative movement in either direction and provided with a lost motion slot, a yieldable stop associated with the rod, and a grip mounted on the bar and coacting with the stop to prevent relative movement of the bar in one direction when subjected to a pressure less than a predetermined value.

5. An automatic slack adjuster as in claim 4, and spring means for maintaining the grip in a holding position.

6. An automatic slack adjuster comprising an adjustable push rod and holding means coacting with the parts thereof to maintain the rod in extended positions to hold slack taken up thereby, in combination with an auxiliary adjusting device to extend the rod, said device including an adjusting bar slidably supported by the rod, and a connection between the rod and bar adapted to yield to relative longitudinal movement of the bar in both directions. saidconnection comprising a grip mounted on the bar, a movable stop associated with the rod, and spring means engaging the stop and the grip and tending to maintain both in ope 'ative position as described.

7. An automatic slack adjuster comprising a two-part telescopic push rod and holding means coacting with the parts to maintain the rod in extended positions, in combination with an adjusting device adapted to hold one of the parts while the other part is pulled out thereby to extend the rod to take up slack, said device comprising an adjusting bar and a stop both movably supported by one of said parts, a grip on the bar and coacting with the stop to prevent inward movement of the bar when subjected to a pressure less than a predetermined value but permitting free outward movement thereof,

a spring engaging the stop and a second spring engaging the grip whereby the stop and grip are each maintained in operative position, and means for releasing the grip to permit inward movement of the bar when subjected to the predetermined amount of pressure.

8. An automatic slack adjuster as in claim 7, the last mentioned means consisting of a tripping lug associated with one of the parts of the push rod.

9. In a device of the character described apush'rod comprising an outer and an inner part in telescopic relation and means coacting with the parts to hold slack taken up thereby, in combination with an auxiliary adjusting device adapted to hold one of the parts of the push rod while the other part is being pulled out, said device comprising an adjusting bar passing through a housing associated with the outer part of the push rod, a yieldable stop mounted in the housing, a grip on the bar within the housing, a spring compressed between the stop and one wall of the housing for holding the stop in operative position, a second spring compressed between the opposite wall of the housing and the grip for' holding the grip in engagement with the stop and in interlocked relation with the bar to prevent inward movement of the bar when subjected to a pressure less than a predetermined value but permitting outward movement thereof, and a tripping lug in the housing for releasing the grip to permit inward movement of the bar when subjected to pressure equal to or greater than the predetermined value.

10. In a device of the character described a two-part telescopic push rod and an adjusting bar, one of said parts comprising a chamber through which the bar passes, a spring controlled stop mounted in the cha1nher at one side of the bar, a tripping lug in the chamber anddisposed at the opposite side of the bar, a grip on the bar within the chamber, and a spring for maintaining the grip in holding engagement with the stop and the bar, said grip permitting free outward movement of the bar and coacting with said lug to permit inward movement of the bar when subjected to pressure exceeding a predetermined amount, substantially as and for the purpose described.

11. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device, said device embodying an adjusting bar slidably supported by said push rod, and a connection between the rod and bar adapted to permit free movement of the bar in one direction and hold the parts against movement in the opposite direction until a predetermined pressure has been reached, and to automatically release the connection and permit movement of the bar when subjected to the predetermined amount of pressure.

12. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device, said device embodying an adjusting bar slidably supported by the push rod, a grip mounted on the bar and permitting free movement of the bar in one direction and a yielding stop to engage the grip and prevent movement of the bar in the other direction until the bar is subjected to a predetermined pressure.

18. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device, said device embodying an adjusting bar slidably supported by the push rod, a grip mounted on the bar and permitting free movement of the bar in one direction, a yielding stop to engage the grip and prevent movement of the bar in the other direction until the bar is subjected to a predetermined pressure, and means to engage and release the grip from the bar when the predetermined pressure has been reached and permit free movement of the bar in the last named direction.

14. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device, said device embodying an adjusting bar slidably supported by the push rod, a grip mounted on the bar and permitting free movement of the bar in one direction and a yielding stop engaging the grip and maintaining the grip in a holding relation with the bar and permitting a limited movement of the bar and grip in the other direction after a predetermined pressure has been applied to the bar.

15. An automatic slack adjuster comprising an adjustable push rod and holding means therefor, in combination with an auxiliary adjusting device. said device embodying an adjusting bar slidably supported by the push rod, a grip mounted on the bar and permitting free movement of the bar in one direction, a yielding stop engaging the grip and maintaining the grip in a holding relation with the bar and permitting a limited movement of the bar and grip in the other direction after a predetermined pressure has been applied to the bar and means releasing the bar and grip after the bar has moved the limited amount and permitting free movement of the bar in the last named direction.

In testimony whereof I aflix my signature.

VALTER HUNZICKER. 

